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This paper presents numerical solutions for determining the uplift capacity of strip plate anchors embedded at different positions either from the toe or crest of cohesive-frictional soil slope. Finite element method based on lower bound theorem of limit analysis in combination with second-order cone programming has been used for obtaining the solutions. Dimensionless uplift factors are used for estimating the ultimate uplift resistance of anchors due to contribution of cohesion, unit weight and angle of internal friction of soil. For different edge-distance of anchor either from the crest or toe of the slope, computations are carried out for different combinations of internal friction angle of soil, angle and height of sloping surface, normalised strength of soil, and embedment ratio of anchors. The uplift capacity has been found to remain the same within a zone extending from the middle of the slope towards both toe and crest of sloping ground. [ABSTRACT FROM AUTHOR]

Despite numerous applications of helical anchors in slope stabilisation and retaining wall construction, a limited number of studies have been conducted on their performance. In the present study, the results of investigating 4 types of helical anchors and three configurations of reinforcement are presented. The tests were carried out on sandy soil using a test box, load cell, indicator, and 5 dial gauges. The present work aims to evaluate the effect of anchor geometry and its configuration on wall displacement. In all tests, particle image velocimetry (PIV) method was applied to study the shape of the slip surface. The results showed that diamond configuration outperforms square one in terms of bearing capacity, wall crest displacement, and its deformation. Moreover, in all tests, an increase in the number of helices resulted in a descending trend in bearing capacity increase and a decrease in wall displacement, suggesting the reduction of efficiency by increasing the number of plates. The results also show that anchor configurations and the number of helices are more effective than the number of anchors in increasing the bearing capacity. [ABSTRACT FROM AUTHOR]

Vertical anchor plates are often provided to increase the performance of various geotechnical engineering structures such as sheet pile walls, bulkheads, bridge abutments and offshore structures. Hence, the safe design of such structures needs a better understanding of the 3D behaviour of the anchor plate. This paper presents and discusses the results obtained from a series of 3D finite-difference analyses of vertical square anchor plate embedded in cohesionless soil. The 3D model is found to closely predict experimental pullout load–displacement relationship. The failure mechanism observed in the numerical model is found to be very similar to the failure reported in experimental studies. For a given embedment depth, the stiffness of the breakout factor–displacement response substantially reduces with increase in anchor plate size. However, the ultimate reduction in anchor capacity is found to approximately 8% with an increase in anchor size from 0.1 to 1 m. Numerical analysis reveals that at deeper embedment depth, the friction angle of sand is the critical parameter in enhancing the performance of anchor plate. The obtained 3D model results are then compared with the published results and are found to be reasonably in good agreement with each other. [ABSTRACT FROM AUTHOR]

In this paper, the feasibility of using evolutionary computing for solving some complex problems in geotechnical engineering is investigated. The paper presents a relatively new technique, i.e. evolutionary polynomial regression (EPR), for modelling three practical applications in geotechnical engineering including the settlement of shallow foundations on cohesionless soils, pullout capacity of small ground anchors and ultimate bearing capacity of pile foundations. The prediction results from the proposed EPR models are compared with those obtained from artificial neural network (ANN) models previously developed by the author, as well as some of the most commonly available methods. The results indicate that the proposed EPR models agree well with (or better than) the ANN models and significantly outperform the other existing methods. The advantage of EPR technique over ANNs is that EPR generates transparent and well-structured models in the form of simple and easy-to-use hand calculation formulae that can be readily used by practising engineers. [ABSTRACT FROM PUBLISHER]

In the presence of pseudo-static horizontal earthquake body forces and horizontal seepage forces, the vertical pullout capacity of horizontal plate anchors buried in sand has been determined by using the lower bound theorem of the limit analysis in combination with finite elements and linear optimisation. The variations of the pullout factor (a)Fγwith, and (b) the factorFqwithαh, have been established for different embedment ratio of the anchor plate and the friction angle of sand. It is noted that the pullout capacity decreases continuously with increases in the values ofαhand. The pullout capacity becomes continuously higher for greater values of the embedment ratio and interface friction angle. The failure patterns have been found to become unsymmetrical in the presence of horizontal body forces. [ABSTRACT FROM AUTHOR]

Presently, no displacement-based design methodology exists for helical anchors subjected to tensile or uplift loading. This study investigates the statistical and probabilistic aspects of the load-displacement uncertainty associated with a database of thirty-seven uplift loading tests of helical anchors founded within cohesive soils. Initially, an ultimate resistance model is identified, and the semi-empirical uplift breakout factor statistically characterized. A relationship between ultimate resistance and slope tangent capacity is established, and used to form the basis for normalizing the load-displacement response. Hyperbolic and power law models are statistically evaluated for use in serving as a reference load-displacement model; the hyperbolic curve was selected based on goodness-of-fit statistics. Monte Carlo reliability simulations are used to establish an equivalent-deterministic load factor that associates the selected load factor with a probability of exceeding a pre-determined allowable uplift displacement, given uncertainty in the undrained shear strength, ultimate resistance model, transformation uncertainty, uncertainty in the allowable displacement, and variability in uplift loading. A practical example is provided to show the intended use of this probabilistic helical anchor displacement model. [ABSTRACT FROM AUTHOR]

The horizontal pullout capacity of vertical anchors embedded in sand in the presence of pseudo static horizontal earthquake body forces has been determined by using the lower bound finite element limit analysis. The variation of the pullout factor Fγwith changes in embedment ratio of the anchor plate for different values of horizontal earthquake acceleration coefficient (αh) has been established. The effect of the anchor-soil interface friction angle on the results has also been examined. The pullout capacity decreases quite significantly with an increase in αh. The pullout capacity becomes higher for greater values of embedment ratio and interface friction angle. The normal pressure distribution along the front surface of the anchor plate and the development of failure patterns have also been examined. [ABSTRACT FROM PUBLISHER]

Plate anchor is one of the most common varieties of anchors used in the construction and maintenance work of various on-land and offshore structures. An accurate estimation of the uplift capacity of anchor foundations is necessary for an economical design as well as for the safety and stability of structures. This paper outlines the effect of shape of anchor plates on their breakout capacity, through a series of model tests. Both shallow and deep anchor behaviours were investigated under conditions developing suction force and without suction force. The results of these tests are presented in terms of load-displacement behaviour, variation of breakout factors (with and without suction force) with depth of embedment, the critical embedment depth of anchors and variation of suction force with embedment ratio. Further, the variations of breakout factor ratio with aspect ratio and embedment ratio are reported. Based on the experimental results and the model test results of other investigators an empirical relationship has been suggested to determine the shape factor and holding capacity of plate anchors buried in saturated cohesive soils. [ABSTRACT FROM AUTHOR]